The invention is in the field of semiconductor devices, and relates more specifically to multiple semiconductor chip (hereinafter multi-chip) modules for use in power applications.
Multi-chip module technology has recently been applied to integrated circuits used in high power applications, such as power supplies and electronic ballast circuits. Such multi-chip modules typically include at least a power semiconductor chip and a control semiconductor chip mounted on an electrically conductive (typically metal) heat sink. In the prior art, one or more of the chips employed in the module must be electrically insulated from the metal heat sink in order to maintain electrical isolation, thus requiring a relatively complicated structure which is costly to manufacture. Additionally, such a configuration is not ideal in terms of electrical performance, because electrically isolating one or more chips from the metal heat sink and having the heat sink float at other than ground potential may result in electromagnetic interference (EMI).
A typical prior-art device configuration is shown in Japanese patent abstract JP 6-169057A. In the elementary multi-chip module shown in this reference, one chip is shown as soldered directly to a heat sink, while a second chip is provided on an electrode plate, which is in turn provided on an insulating ceramic plate provided on the heat sink.
While the foregoing structure permits the fabrication of a multi-chip module incorporating different chip types and functions, it is relatively complicated and therefore uneconomical to manufacture, and in certain applications structures of this type will generate electromagnetic (EMI) radiation.
Accordingly, it would be desirable to have a multi-chip module for use in power applications which is simple in construction and therefore economical to fabricate, and in which performance parameters such as reduced EMI are enhanced.
It is therefore an object of the present invention to provide a multi-chip module for use in power applications which is simple in construction, economical to fabricate, and capable of offering enhanced performance.
In accordance with the invention, these objects are achieved in a multi-chip module of the type described above in which a plurality of semiconductor chips are all directly mounted on an electrically conductive heat sink without the use of a separate electrical insulation layer.
In a preferred embodiment of the invention, the multi-chip module includes at least a power semiconductor chip having a silicon-on-insulator (SOI) device and a control semiconductor chip having a semiconductor device with a substrate connected to ground potential, with both the power semiconductor chip and the control semiconductor chip being directly mounted on the electrically conductive heat sink without the use of a separate electrical insulation layer.
In further preferred embodiments of the invention, the control semiconductor chip includes BIMOS, bipolar, or CMOS devices and has a substrate connected to ground potential.
Multi-chip modules in accordance with the present invention offer a significant improvement in that a simple, economical configuration having improved performance characteristics is achieved.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.